Biomedical subjects

S Jancar

Publications and source records attributed to S Jancar.

At least 19 recordsLinked to original sources

PubMed2006

Effect of endothelins on human neutrophil activation by immune complexes.

Neutrophils are important effector cells of tissue injury in several pathological conditions, among them, immune complexes (IC)-induced inflammation and tissue injury. There is evidence that endothelins modulate IC-induced tissue injury in experimental models in vivo. In the present study we investigated the effect of endothelins on neutrophil activation by IC in vitro. To this purpose, pre-formed insoluble immune complexes were used to stimulate human neutrophils and production of leukotriene B(4) (LTB(4)) and hydrogen peroxyde (H(2)O(2)) were measured as indicative of phospholipase A(2) and oxidative burst activation and myeloperoxidase (MPO) release as indicative of cell degranulation. The effect of endothelins (ETs) in these events induced by IC was then examined. We found that IC stimulated all three events in human neutrophils. Addition of ET-1 but not ET-2 or ET-3 to the IC-stimulated neutrophils potentiated LTB(4) but not H(2)O(2) production. The endothelins added to resting neutrophils did not induce LTB(4) production but they were effective to stimulate H(2)O(2) production. The increased MPO activity induced by IC was not affected by endothelins nor did they stimulate the release of this enzyme in resting cells. These results show that endothelins are able to activate some neutrophil functions and to upregulate the IC-induced production of the pro-inflammatory molecule LTB(4). These data indicate that products of endothelial cells, such as endothelins, can be involved in the potentiation of neutrophil-dependent tissue injury.

Antibodies↗

PubMed2005

Role of insulin on PGE2 generation during LPS-induced lung inflammation in rats.

Alterations in arachidonic acid (AA) metabolism have been reported to occur in diabetes mellitus. The present study was carried out to verify if these alterations are due to the relative lack of insulin or to high levels of blood glucose. Male Wistar rats were rendered diabetic by alloxan injection (42 mg/kg, i.v.), 10 or 30 days before the experiments. Some diabetic rats received a single dose (4 IU, s.c.) of NPH insulin 2 h before an intratracheal instillation of lipopolysaccharide (LPS, 750 microg) or saline. Six hours after LPS challenge, the following parameters were analysed: blood glucose levels, total and differential leukocyte counts in bronchoalveolar lavage (BAL) fluid; linoleic acid and AA content in blood neutrophils (HPLC), and levels of prostaglandin (PG)E(2) in BAL (ELISA). Relative to controls, a reduced number of neutrophils (18%) and decreased amounts of PGE(2) (40%) were observed in the BAL fluid of diabetic rats in response to LPS. A single dose of insulin was not able to reduce blood sugar levels to normal values, but instead resulted in the normalization of both leukocyte migration to the lungs and levels of PGE(2). Accordingly, these abnormalities might be primarily linked to a continuing insulin deficiency rather than to secondary hyperglycaemia occurring in the diabetic rat. In conclusion, data presented suggest that insulin might regulate neutrophil migration and generation of PGE(2) during the course of acute lung injury induced by LPS.

Alloxan↗

PubMed2004

Modulation of allergic and immune complex-induced lung inflammation by bradykinin receptor antagonists.

OBJECTIVE: The effect of bradykinin (B(1) or B(2)) receptor antagonists was studied in allergic and immune-complex-induced lung inflammation. METHODS: Lungs of BALB/c mice were examined 24 h after induction of lung inflammation, either allergic (ovalbumin-sensitized submitted to two aerosol of antigen, one week apart) or immune-complex induced (intratracheal instillation of IgG antibodies followed by intravenous antigen). The bradykinin B(2) receptor antagonist, HOE-140 or bradykinin B(1) receptor antagonist, R-954 were given intraperitoneally (100 microg/kg), 30 min before induction. RESULTS: In allergic inflammation, pre-treatment with R-954 reduced eosinophil infiltration into the lungs, mucus secretion and the airway hyperreactivity to methacholine. Pre-treatment with HOE-140 increased eosinophil infiltration but did not affect the other parameters. In immune-complex inflammation, HOE-140 increased neutrophil infiltration but not their activation nor the hemorrhagic lesions. R-594 pre-treatment did not change the parameters examined. CONCLUSION: These results show important modulatory effects of bradykinin B(1) and B(2) receptor antagonists in both models of lung inflammation.

Animals↗

PubMed2004

Evidence that arachidonic acid derived from neutrophils and prostaglandin E2 are associated with the induction of acute lung inflammation by lipopolysaccharide of Escherichia coli.

OBJECTIVE: The involvement of arachidonic acid (AA) and PGE2 during the E. coli lipopolysaccharide (LPS)-induced acute lung injury was investigated. MATERIAL: Adult male Wistar rats were used. For in vitro studies, rat neutrophils, bronchoalveolar lavage (BAL) fluid, and lug vascular endothelium were used, as described below. TREATMENT: Rats were given an intratracheal injection of LPS (750 microg). METHODS: Total and differential cell counts in BAL fluid; enzyme-linked immunoassay (ELISA) analyses of TNF-alpha, IL-1beta, LTB4 and PGE2 in BAL, and immunohistochemical detection of ICAM-1 on lung vascular endothelium were performed six h after LPS challenge. Fatty acid composition of blood neutrophils and plasma was analyzed by HPLC. RESULTS: Rats instilled with LPS presented a sixty three-fold increase in the number of neutrophils in BAL (from 0.5 x 10(6) to 31.5 x 10(6) cells), accompanied by increased levels of TNF-alpha and IL-1beta (p < 0.001), and a three-fold increase in ICAM-1 expression on vascular endothelium. The content of AA in blood neutrophils was reduced by 50%, whereas the level of PGE2 in BAL was increased by 3.5 fold, without changes in the levels of LTB4. CONCLUSIONS: These findings suggest that AA and PGE2 are associated with LPS challenge.

Acute Disease↗

PubMed2004

Association of endothelin with lung hemorrhage induced by immune complexes in rats.

The participation of endothelins (ETs) in a model of neutrophil-dependent lung injury induced by intrabronchial instillation of rabbit antibodies to ovalbumin followed by i.v. injection of the antigens (Arthus reaction) was investigated. Hemorrhagic lesions were evaluated by measuring the extravasations of hemoglobin in lung parenchyma. From 5 min to 24 h after the Arthus reaction (AR), endothelin (ir-ET) levels in bronchoalveolar lavage fluid (BALF) and in plasma were measured by radioimmunoassay. BALF levels of ir-ET were not different between control and AR animals for the first 90 min after the antigen challenge but increased from 2 to 24 h after induction of AR. ET levels in the plasma did not change from the respective controls over the same 24 h period. Increased ir-ET in BALF was not affected by pretreatment with L-NAME (30 mg/kg, i.v.). A PAF antagonist (BN52021; 5 and 10 mg/kg, i.v.) increased ET content in BALF and decreased the intensity of the AR. Thiorphan (2 mg/kg, i.v.) inhibited the AR-induced hemorrhagic lesions in lungs. An ET(A) receptor antagonist, BQ-123 (1 mg/kg, i.v.) potentiated, whereas the ET(B) antagonist, BQ-788 (1 mg/kg, i.v.) inhibited the lung hemorrhage. It is concluded that ETs are released during and play a role in the lung AR.

Animals↗

PubMed2003

Increased microvascular permeability in the hamster cheek pouch induced by oxidized low density lipoprotein (oxLDL) and some fragmented apolipoprotein B proteins.

OBJECTIVE AND DESIGN: Oxidized low-density lipoproteins (oxLDL) and protein fractions obtained by size exclusion chromatography of oxLDL were tested for vascular permeability effects on topical application to the hamster cheek pouch. MATERIALS: The hamster cheek pouch was prepared for intravital microscopy observations of macromolecular leakage at post capillary venules (=leaks) with FITC-dextran as tracer. TREATMENT: OxLDL (0.1 mg/ml), PAF (platelet activation factor, 50-100 nM) and protein fractions of oxLDL (10 microg/ml) were applied topically to hamster cheek pouches. RESULTS: Application of oxLDL and PAF resulted in reversible increases in the number of leaks. The PAF-antagonist WEB 2170, L-NAME and a beta(2)-adrenoceptor agonist inhibited (P<0.01) almost completely the macromolecular leakage induced with oxLDL or PAF. Protein fractions were found to be more effective than unfractionated oxLDL in inducing plasma leakage as calculated on mg/ml-basis. CONCLUSION: Hamster oxLDL is a potent inducer of macromolecular leakage increase in the hamster cheek pouch microcirculation. The principal effect is mediated by PAF-like structures produced by the oxidation of the LDL-particle but oxLDL also contains low molecular weight proteins that could contribute to the overall vascular permeability increasing effect of ox LDL.

Adrenergic beta-2 Receptor Agonists↗

PubMed2002

Impact of parenteral n-3 fatty acids on experimental acute colitis.

The present study was undertaken to investigate the effects of parenteral lipid emulsions (LE) enriched with n-3 fatty acids (n-3 FA) in experimental acute colitis. Seventy-four adult male Wistar rats were randomized into six groups, five of which had acetic acid-induced colitis. The animals received a fat-free diet and water ad libitum in individual metabolic cages. By a central venous catheter, saline was infused (0.5 ml/h) into the control groups CS (without colitis) and CC (with colitis), while the test groups received specific LE for 7 days. The n-3/n-6 FA ratio and the lipidic compositions regarding long chain (LCT) and medium chain (MCT) triglycerides were: group L--1:7.7 (LCT, n = 12), M--1:7.0 (MCT and LCT, n = 12), LW-3--1:4.5 (LCT plus n-3 FA, n = 12) and MW-3--1:3.0 (MCT and LCT plus n-3 FA, n = 13). The frequency of diarrhea, oral intake/body weight ratio, intestinal alterations, macrophage cellularity were evaluated and colonic concentrations of leukotrienes (LTB4, LTC4), prostaglandins (PGE2) and thromboxanes (TXB2) were measured. Groups M, MW-3 and LW-3 had less diarrhea than the CC group (P<0.05). Average oral intake/body weight ratio in MW-3 animals was comparable to the CS and better than the CC group. n-3 FA treated rats (LW-3 and MW-3) presented less intestinal inflammatory alterations than CC rats. Mucosal ulcer formation in MW-3 group did not differ from CS rats. M and MW-3 rats had less macrophages in the colon than the CC group. Compared with CC group, lower concentrations of LTB4 in the CS, LW-3 and MW-3 groups; of PGE2 in the CS, M and MW-3 groups; and of TXB2 in the CS and MW-3 groups were found. Mean concentrations of LTC4 did not differ among the groups. Thus, a LCT-containing LE with a low n-3-n-6 ratio does not modify inflammatory colitis manifestations; LE with a high n-3-n-6 ratio reduces diarrhea, preserves oral intake-weight ratio, attenuates morphological consequences and decreases colonic concentrations of inflammatory mediators; MCT/LCT-containing LE with 1:3 n-3-n-6 ratio exerts the most profound beneficial impact on the inflammatory response.

Acute Disease↗

PubMed2001

Antigen-induced bronchial hyperreactivity and bronchopulmonary inflammation in rats: effect of TNF receptor binding protein.

The effect of a receptor binding protein for tumor necrosis factor (TNFrbp) on cell infiltration, bronchial hyperreactivity, and release of inflammatory mediators were studied following antigen challenge in sensitized rats. A 3-fold increase in total cell number, mainly neutrophils and eosinophils, was noted in bronchoalveolar lavage (BAL) fluid 8 hours after antigen challenge. Antigen challenge also induced a significant hyperreactivity of the lower bronchus to carbachol and serotonin, but did not affect the reactivity of the trachea and upper bronchus. This increased responsiveness of the lower bronchus was transient, being detected 8 hours but not 24 hours after antigen challenge. Thromboxane B2 (TxB2), prostaglandin E2 (PGF2), and nitric oxide (NO) levels increased in the BAL fluid of sensitized rats 8 hours after antigen challenge by 197%, 172%, and 173%, respectively. TNFrbp treatment reduced by 83% the antigen-induced cell infiltration, with neutrophils being the cells most affected. The bronchial hyperreactivity induced by antigen challenge was also significantly inhibited by TNFrbp, whereas TxB2, PGE2, and NO levels in the BAL fluid were not affected. In our animal model, the cell infiltration and bronchial hyperreactivity appear to be mediated to some extent by TNF, but not by prostanoids nor NO.

Animals↗

PubMed2000

Discrimination between NK and LAK cytotoxic activities of murine spleen cells by MTT assay: differential inhibition by PGE(2) and EDTA.

In the present study we propose a mathematical approach to improve the analysis of NK and LAK activities measured by MTT assay adapted for murine cells. We found that to calculate NK activity, high E:T ratios should be used (up to 50:1) and the phenomenon fits to a linear least-squares analysis. However, 5-fold less effector cells (10:1, E:T) should be used to detect LAK activity and the phenomenon has a nonlinear exponential behavior. Using this approach, we showed that EDTA inhibits LAK but not NK activity whereas PGE(2) inhibits NK but not LAK activity. In conclusion, this analytical approach allowed the discrimination between NK and LAK activities and exposed differences between these two cytotoxic activities.

Animals↗

PubMed2000

Reduced inflammatory response in rats fed fat-rich diets: role of leukotrienes.

The effect of fat-rich diets on the acute inflammatory response was examined. Male Wistar rats aged 21 days were fed, for 6 weeks, with a control diet (4% fat content), or a control diet supplemented with coconut or soybean oils (15% fat content). Carrageenan-induced paw oedema and pleurisy were evaluated. Prostaglandin (PG) E2 and leukotriene (LT) C4/D4 concentrations were determined in the pleural exudate (ELISA). Pleural samples were tested for their effect on cutaneous vascular permeability of control rats and the effect of a LTD4 receptor antagonist (L660-711; 10 mg/kg; i.v.) examined. Relative to controls, rats fed both fat-rich diets presented a significant reduction in protein leakage and oedema formation without affecting the number of migrating leukocytes. Production of LTC4/D4 in pleural exudate was significantly increased from 1.8 +/- 0.2 ng/ml in controls to 2.8 +/- 0.2 and 3.0 +/- 0.3 ng/ml in animals fed coconut and soybean oil enriched diets, respectively, without changes in PGE2 production. The activity of these samples on cutaneous vascular permeability was 50% reduced, returning to control values after treatment of testing animals with a LTD4 receptor antagonist. Rats fed fat-rich diets presented a reduced inflammatory response due, at least in part, to the LTC4/D4 mediated vasoconstrictor effect.

Acute-Phase Reaction↗

PubMed2000

Essential role of platelet-activating factor in control of Leishmania (Leishmania) amazonensis infection.

In the present study we investigated the role of platelet-activating factor (PAF) and prostaglandins in experimental Leishmania (Leishmania) amazonensis infection and the relationship between these mediators and nitric oxide (NO) production. Mouse peritoneal macrophages elicited with thioglicolate were infected with leishmania amastigotes, and the infection index determined 48 h later. The course of infection was monitored for 5 weeks in mice infected in the footpad with promastigotes by measuring the footpad swelling and parasite load in regional lymph nodes and spleen. The addition of PAF to C57BL/6 mouse macrophages significantly inhibited parasite growth and induced NO production. Treatment of macrophages with a selective PAF antagonist, WEB2086, increased the infection, indicating that endogenously produced PAF regulates macrophage ability to control leishmania infection. This effect of PAF was abolished by addition of the inhibitor of NO synthesis, L-NAME, to the cultures. The addition of prostaglandin E(2) significantly increased the infection and NO production. Treatment with cyclo-oxygenase inhibitor, indomethacin, reduced the infection and PAF-induced release of NO. Thus, the increased NO production induced by PAF seems to be mediated by prostaglandins. The more-selective inhibitors of cyclo-oxygenase 2, nimesulide and NS-398, had no significant effect. Thus, antileishmanial activity correlates better with the presence of PAF or absence of prostaglandins than with NO production. In vivo treatment with PAF antagonists significantly increased leishmania lesions, as well as the parasite load, in regional lymph nodes and spleens. These findings indicate that PAF is essential for the control of leishmania infection.

Animals↗

PubMed1999

Platelet-activating factor and eicosanoids are mediators of local and systemic changes induced by immune-complexes in mice.

A passive Arthus reaction (AR) induced in the peritoneal cavity of mice was followed by increased local vascular permeability and haemoconcentration. The intensity of the increased vasopermeability was higher in BALB/c compared with C3H/HePas mice despite the latter being 10 times more sensitive to platelet-activating factor (PAF). C3H/HePas mice however, exhibited higher levels of haemoconcentration and shock-like symptoms. Both events were inhibited by the PAF antagonist, WEB 2170. Indomethacin reduced both pathological events whereas L663,536, that inhibits leukotrienes synthesis reduced haemoconcentration but only in BALB/c mice. PAF was released into the peritoneal cavity, peak release being at 10 min after induction of AR. Prostaglandin E2 (PGE2), thromboxane B2 (TXB2), leukotriene B4 (LTB4), and leukotriene C4/D4 (LTC4/D4) were also released at this time. Similar levels of PAF and eicosanoids were found in BALB/c and C3H/HePas mice except for LTB4, which was higher in C3H/HePas. It is concluded that PAF and eicosanoids are mediators of local and systemic changes induced by immune complexes in the peritoneal cavity of mice.

Animals↗

PubMed1999

A rat model presenting eosinophilia in the airways, lung eosinophil activation, and pulmonary hyperreactivity.

The aim of this study was to examine antigen-induced lung cell migration, eosinophil activation, and pulmonary reactivity of Wistar rats exposed to a new sensitization technique. The animals were sensitized with a single subcutaneous implant of a fragment of heat coagulated hen egg white and challenged 21 days later with an intratracheal injection of heat-aggregated ovalbumin (EWI). For comparison, another group of rats were sensitized by an intraperitoneal injection of ovalbumin in alum as adjuvant, with one booster on day 14 and challenge on day 21 post immunization (OVA/AL). Twenty-four hours after antigen challenge, the EWI group presented a higher number of eosinophils in the bronchoalveolar lavage (BAL) (4.85 +/- 1.43 x 10(6)) than the OVA/AL group (0.2 +/- 0.06 x 10(6)) or the control group, where the level of eosinophils were essentially undetectable. Levels of eosinophil peroxidase activity were increased in the cell-free BAL and homogenates of lung tissue in the EWI group (12.10 +/- 2.97 mg/mL and 36.14 +/- 7.21 ng/mg, respectively), but not in the OVA/AL group (4.83 +/- 1.4 ng/mL and 11.95 +/- 2.54 ng/mg, respectively), as compared with controls (5.16 +/- 1.65 ng/mL and 12.13 +/- 1.74 ng/mg, respectively). Thromboxane B2 levels were also increased in the BAL of EWI group (2.89 +/- 0.54 ng/mL) but not the OVA/AL group (1.13 +/- 0.23 ng/mL) as compared with controls (1.14 +/- 0.19 ng/mL). In contrast, the levels of prostaglandin E2 in the BAL were increased in both groups (456.4 +/- 11.8 pg/mL in the EWI group and 303.5 +/- 31.7 pg/mL in the OVA/AL group) as compared with controls (205.7 +/- 29.7 ng/mL). Moreover, only the EWI group developed increased pulmonary reactivity to serotonin (around two-fold), 24 hours after antigen challenge. The extent of lung eosinophil migration and activation and the pulmonary hyperreactivity induced by this novel sensitization procedure without adjuvants represents a significant improvement over existing experimental models of asthma.

Animals↗

PubMed1999

Mycoplasma arginini enhances cytotoxicity of thioglycollate-elicited murine macrophages toward YAC-1 tumor cells through production of NO.

Bacterial products stimulate macrophage tumoricidal activity through release of tumor necrosis factor (TNF) and nitric oxide (NO). We show here that thioglycollate-elicited macrophages acquire cytotoxic activity when cocultured with Mycoplasma arginini-infected YAC-1 tumor cells and release TNF and NO. Fixed mycoplasma-infected cells, supernatants from infected-cell cultures, or purified heat-killed mycoplasma obtained from cell-free cultures were all able to induce TNF and NO production. Thus, the mycoplasma per se and not a product of infected cells induce the release of these molecules. Addition of prostaglandin E2 (PGE2) to the cocultures, which reduced TNF release, or antibodies to TNF, did not affect macrophage cytotoxicity nor NO release. Inhibition of NO production by L-NAME or aminoguanidine reduced the cytotoxicity, and treatment with a NO donor was toxic to YAC-1 cells. These results indicate that M. arginini activates thioglycollate-elicited murine macrophages for NO and TNF release increasing their cytotoxic activity toward YAC-1 cells and that this activity is dependent on NO but not TNF release.

Animals↗

PubMed1998

Modulation by lipid mediators of immune complex-induced lung inflammation in mice.

The present study characterized a murine model of immune complex-induced pneumonitis and investigated the role of platelet-activating factor (PAF) and eicosanoids as mediators of lung neutrophil infiltration and hemorrhagic lesions. Rabbit antibodies to bovine serum albumin were injected into the airways and bovine serum albumin was injected intravenously into C3H/HePas and BALB/c mice. After 24 h, a significant increase in neutrophil infiltration and hemoglobin concentration in the bronchoalveolar lavage fluid and lung parenchyma was observed in both strains despite the C3H/HePas strain being 10 times more sensitive to PAF. Neutrophil influx and vascular lesions were not affected by pre-treatment of the mice with the PAF receptor antagonist, WEB 2170 (5-(2-chlorphenyl)carbonyl)-3,4-dihydro- 10-methyl-3-((4-morpholinyl)-2H,7H-cyclopenta(4,5)thieno(3,2-f)(1,2,4)-t riazolo-(4,3-a)(1,4)-diazepine). In contrast, neutrophil influx and vascular lesions were increased by the cyclo-oxygenase inhibitor, indomethacin, and reduced by the inhibitor of leukotriene synthesis, MK 886 (3-[1-(4-chlorobenzyl-3-t-butyl-thio-t-isopropyl-indol-2y-1]-2-2-+ ++dimethylpropanoic acid) and by the leukotriene B4 receptor antagonist, RO 0254094 (2-[(5-carboxypentyl)-6-[6-[3,4-dihidro-4-oxo-8-propyl-2H-1-benzop yran-7-yl)hexyl] benzenepropanoic acid). Increased levels of leukotriene B4, leukotriene C4/D4, thromboxane B2 were found in bronchoalveolar lavage fluid 4 h after induction of the reaction. There is also a tendency to increased prostaglandins E2 levels. Neutrophil infiltration and vascular lesions in immune complex-induced pneumonitis in mice are mediated by leukotriene B4.

Animals↗

PubMed1998

Lipid mediators, tumor necrosis factor and nitric oxide and their interactions in immune-complex-induced lung injury.

We investigated the contribution of eicosanoids, platelet-activating factor, tumor necrosis factor and nitric oxide to the neutrophil influx and development of pulmonary haemorrhagic lesions following immune-complex-induced pneumonitis in rats and possible interactions between these mediators. Increased levels of leukotriene B4 and tumor necrosis factor, measured by enzyme immunoassay and L-929 cytotoxicity assay, were found in the bronchoalveolar lavage 1 and 4 h after induction of the reaction, respectively, and their release was dependent on the previous generation of platelet activating factor. Antagonism of leukotriene B4 receptors by RO-0254094 (2-[(5-carboxypentyl])oxy]-6-[6-[3,4-dihydro-4-oxo-8-propyl-2H-1-benzopy ran-7-yl)oxy]hexyl] benzenepropanoic acid), inhibition of nitric oxide synthesis by L-NAME (Nw-nitro-L-arginine methyl ester) and antagonism of PAF-receptors by WEB-2170 (5-(2-chlorphenyl)-3-4-dihydro-10-methyl-3-((4-morpholinyl)carbony l)-2 H,7H-cyclopenta (4,5)thieno(3,2-f)(1,2,4)-triazolo-4,3,a)91,4)diazepine), significantly inhibited the intensity of haemorrhage, evaluated by the increased levels of extravascular hemoglobin in homogenates of lung tissues. Little evidence support the role of tumor necrosis factor in these lesions. The infiltration of neutrophils, evaluated by measuring myeloperoxidase in homogenates of lungs, was reduced by compounds L-663,536 (3-[1-(4 chlorobenzyl)-3-t-butyl thio-5-isopropylindol-2-yl]-2-2-dimethylpropanoic acid), WEB-2170 and L-NAME. These results indicate that neutrophil infiltration and haemorrhagic lesions in immune-complex-induced lung inflammation are mediated by platelet activating factor, leukotriene B4 and nitric oxide and point out to interesting interactions between these mediators.

Animals↗

PubMed1998

Endotoxemic-like shock induced by Loxosceles spider venoms: pathological changes and putative cytokine mediators.

The systemic symptoms, tissue lesions and release of cytokines were analysed in four isogenic mouse strains with distinct haplotypes injected with various doses of Loxosceles intermedia spider venom. The estimated LD50 were 24.5 microg for C57Bl/6, 17.6 microg for BALB/c, 6.3 microg for C3H/HeJ and 4.6 microg for A/Sn mice. Prostration, acute cachexia, hypothermia, neurological disorders and hemoglobinuria were the signals preceding death. Accumulation of eosinophilic material inside the proximal and distal renal tubules and acute tubular necrosis were the most common histopathological findings. Death was prevented by previous treatment of venom with specific antivenom serum. The protein F35 purified from the whole venom retained the ability to induce the symptoms of the whole venom. The cytokines tumor necrosis factor (TNF), interleukins IL-6 and IL-10 and the radical nitric oxide were detected in serum at different levels after venom injection. These findings indicate that the state of shock produced in mice by whole endotoxin-free L. intermedia venom or by its purified fraction, protein F35, mimics the endotoxemic shock, that susceptibility to the systemic effects of the venom varies among mice of different haplotypes and that the pattern of in vivo cytokine release resembles that of endotoxemic shock.

Animals↗

PubMed1998

Prevention of lung eosinophilic inflammation by oral tolerance.

Airway inflammation plays a major role in human asthma. Increasing evidence points to a close correlation between eosinophil infiltration and allergic lung disease. A new murine model of eosinophilic lung inflammation has recently been developed; it consists of immunizing mice with small fragments of solidified hen egg white implanted (EWI) into the subcutaneous tissue. In this model, which is further characterized here, mice challenged with ovalbumin (OVA) present an intense and persistent lung eosinophilia, as well as histopathological findings that resemble human asthma. In the present work, the effect of oral tolerance on the development of allergic lung inflammation in B6 mice immunized with antigen plus adjuvant or with EWI is investigated. It was found that in mice rendered orally tolerant by previous exposure to antigen in the drinking water, the T-helper type 2 cell (Th2)-associated allergic responses in both protocols of immunization were almost completely abolished. The allergic responses were assessed by pulmonary and bone marrow eosinophilia, lung histopathology and antigen-specific IgE and IgG1 production. These findings provide the first indication that Th2-associated lung pathology can be prevented by oral tolerance.

Administration, Oral↗